The Background description provided herein is for the purpose of generally presenting the context of the disclosure. Work of the presently named inventors, to the extent it is described in this background section, as well as aspects of the description which may not otherwise qualify as prior art at the time of filing, are neither expressly or impliedly admitted as prior art against the present disclosure.
Hybrid in-Band, on-Channel (IBOC) radio signals can be used to simultaneously transmit analog FM stereo and digital sideband signals at a common center frequency. In some implementations the IBOC spectrum allocates 400 KHz bandwidth for each channel wherein the analog FM stereo signal is 200 KHz wide and the upper and lower digital sideband signals are each 100 kHz wide. The digital sideband signals can be modulated using quadrature-amplitude modulation (QAM) over upper and lower single-sideband suppressed carrier signals.
IBOC receivers can employ a first downconverter that converts the received IBOC signal to a 10.7 MHz intermediate frequency (IF). A ceramic filter can remove the image component from the received channel. A second downconverter can then be employed to further convert the received signal to a very low IF that can be demodulated in the digital domain. Alternatively, an FM discriminator process can be employed after the ceramic filter to demodulate the received signal. The ceramic filter can be undesirably bulky and/or expensive.